mod_ssl: Fix forever-broken TLS upgrade support; perform the upgrade

mod_ssl: Fix forever-broken TLS upgrade support; perform the upgrade
in the post_read_request hook rather than in a filter, and fix the
filter insertion issue:

* modules/ssl/ssl_engine_kernel.c (upgrade_connection): New function,
mostly moved from ssl_io_filter_Upgrade.
(ssl_hook_ReadReq): Call upgrade_connection to upgrade to TLS if
required.

* modules/ssl/ssl_engine_io.c (ssl_io_filter_Upgrade): Remove
function.
(ssl_io_input_add_filter, ssl_io_filter_init): Take a request_rec
pointer and pass to ap_add_*_filter to ensure the filter chain
is modified correctly; remove it from the filter afterwards.
(ssl_io_filter_register): Drop UPGRADE_FILTER registration.

* modules/ssl/mod_ssl.c (ssl_init_ssl_connection): Take a request_rec
pointer, pass to ssl_io_filter_init.
(ssl_hook_pre_connection): Pass NULL request_rec pointer to above.
(ssl_hook_Insert_Filter): Remove function.
(ssl_register_hooks): Drop insert_filter hook.

* modules/ssl/ssl_private.h: Update prototypes.

PR: 41231

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@592446 13f79535-47bb-0310-9956-ffa450edef68